Atoms-AD,HB

This is a page for all of the notes Adam and I (Halle) take on atoms.

Adam:
From: The book Uranium and other Radioacative Elements
Radioactive Decay

• Radioactive Decay is the gradual release of energy from a radioactive atom.
• Half-life is the point at which an element releases half of it's atoms.
• Although a radioactive atom releases energy during radioactive decay, a radioactive atom will never fully run out of energy.
• Different radioactive atoms have different half-lives. For example the atoms of the element Polonium-210 have a half-life of 138 days compared to the atoms of the element Uranium-238 (my element =>) have a half-life of 4.5 billion years!

Uranium

• Uranium is named after Uranus.
• The element symbol of uranium is U.
• Uranium is silver in color and is very dense.
• In air Uranium creates a blue oxide coating.

http://www.uraniumsa.org/about/discovery.htm

• Uranium was discovered when a german chemist (Martin Heinrich Klaproth) found uranium oxides in a sample of pitchblende (a type of mineral).

http://www.uic.com.au/uran.htm



Plastic sulfur lab



Atom Jokes
A proton, neutron, and electron went out to dinner one night. After a luxurious meal, the waiter brought the check to the proton and the electron. The neutron was perplexed as to why the waiter didn't bring him his check. So, he summoned the waiter to the table and asked him about it.
The waiter explained to the neutron, "For you, there's no charge!"

What do you do with a dead chemist?
- Barium

Q: What happens when electrons lose their energy?
A: They get Bohr'ed.



Halle:

From: http://en.wikipedia.org/wiki/Carbon-14
Carbon-14

• AKA- radiocarbon
• radioactive isotope of Carbon
• 6 protons, 8 neutrons
• After it decays it turns to Nitrogen 14 throught beta decay. (see below)

Radiocarbon Dating

• This uses radiocarbon to determine the age of materials made of carbon.
• It can determine the age of materials up to 60,000 years old.
• The amount of the carbon 14 in the atmosphere at the time the plant or animal died is fixed in the animal.
• By figuring out how much carbon 14 there was the time period can be estimated.
• To figure it out scientists compare the plants or animals with specimens whose age is already determined.
• However, this method is not very accurate for specimens within the last 200 years or so because of all of the fossil fuels being burned.

From: http://www.darvill.clara.net/ntucrad/types.htm
Radioactivity

• When atoms are very unstable they decay into a more stable atom.
• Nothing can change the rate of radioactive decay.
• There are three ways a nucleus can decay:
  • alpha particle
  • beta particle
  • gamma ray
• Gamma rays are not pure, they also give off alpha and beta particles.

Alpha Particles:

• Alpha particles are made of two protons and two neutrons.
• Charge:2 Mass:4
• They are slow and heavy
• Low amount of power (easy to stop)

Beta Particles:

• Charge: -1 Mass:1/2000th of a proton
• About the same as an electron
• They travel fast.
• Medium amount of power (hard to stop)

Gamma Rays:

• They are not particles, they are waves.
• No mass, no charge.
• High amount of power (very hard to stop)
• They travel at the speed of light

From: http://www.pbs.org/wgbh/aso/tryit/atom/elempartp.html
Elementary Particles:

• Atoms are made of electrons and quarks.
  • Quarks are fast-moving points of energy.
  • Electrons are particles that move around the nucleus.
• Neutrons and protons are made of quarks.
  • Each proton and neutron contains 3 quarks.
  • There are up quarks and down quarks.
  • Up quarks have a charge of + 2/3.
  • Down quarks have a charge of -1/3.
  • The sum of quarks in a particle determines its charge.

Stable Atoms:

• A stable atom has a charge of 0.
• This happens when there are equal numbers of protons and electrons.
• If the numbers of protons and electrons are not equal then the atom becomes ionized.
• Atoms that are highly ionized break away from themselves and attach to other atoms.
• Atoms with too little or too many neutrons become radioactive.
• Electrons exist in electron shells.
  • Up to two electrons can exist in the inner shell.
  • Up to eight electrons can exist in the next (g.oing outward) shell
  • An atom can drop and electron shells and form a photon.
    • Photon: a particle with no mass, no charge, and electrical radiation.

Radioactive Decay:

• Radioactive decay occurs when an atom becomes too radioactive.
• Radioactive decay of Carbon-14
  • When carbon-14 decays one of its neutrons turns into a proton.
  • As this happens an electron forms.
  • After this happens carbon-14 becomes nitrogen.